from abc import ABC, abstractmethod
class Notifier(ABC):
    @abstractmethod
    def send_notification(self, message: str) -> None:
        pass

class EmailNotifier(Notifier):
    def send_notification(self, message: str) -> None:

        print(f"Sending email: {message}")

class SMSNotifier(Notifier):
    def send_notification(self, message: str) -> None:

        print(f"Sending SMS: {message}")

class NotificationService:
    def __init__(self, notifier: Notifier):

        self.notifier = notifier

def notify(self, message: str) -> None:
    self.notifier.send_notification(message)

# Usage
email_notifier = EmailNotifier()
email_service = NotificationService(email_notifier)
email_service.notify("Hello via email")